Television apparatus



Aug, 25, 1936. L. DE' FOREST TELEVISION APPARATUS Original Filed April24, 1931 2 Sheets-Sheet 1 a a Z,

amen/00 A566 defireai:

Aug. 25, 1936. 1.. DE FOREST 2,052,133

TELEVISION APPARATUS Original Filed April 24, 1931 2 Sheets-Sheet 2 leedefia (1, 35; I

Patented Aug. 25, 1936 TELEVISION: APPARATUS Lee de Forest, Hollywood,"Calif., assignor to American Television Laboratories, Inc., acorporation of Delaware Original application April 24; 1931, Serial No.

5, apparatus for receiving, and. reproducing tele- Fig. 5.upon ascanningdisk;

vised pictures and images. Fig. 7 is an enlarged sectional view showingIt is well known to those familiar with the the details in theconstruction of a preferred art.that images can be converted intoelectrical form. of individual Kerr celladapted for use. in impulsemodulations which may be transmitted connection with this invention;

by. radio or by wire andreceived at distantpoints, Fig. 8 is a,sectional. view which may be con- 10 where, through the medium. ofso-called' televisidered as having been taken in a plane represionreceiving. apparatus they can be converted sented bythe line 8-8 in Fig.7. into images corresponding to the transmitted As. pointed out above,the method involved in images. The reproduction of the images at thethe. present inventionis one in which the image receiving, station isgenerally accomplished by is produced directly by means of an apertured15 means of a pulsating neon light associated with scanning disk of theusual type, which is pro a scanning disk, and since the quantity of suchvided with novel means adapting the same to use light available. isverysmall, the reproducedimwith a constant light source of highintensity. age is dim. and isincapable of satisfactory mag- Theapparatus. employed, as illustrated in the 20, nification. It,therefore, becomes a primary obdrawings, consists in a general'way of alight ject of this invention to produce an apparatus of source. anda.scanning, disk of the conventional the class described whereby thetelevised'image Nipkow type which are associated wth means may bereproduced with light. of suflicient infor modulating or valvinga brightbeam or area of tensity to permit its: magnification. light by m'eansofa succession of rapidly moving as, Pursuant to the attainment ofthisobject the light valves which are preferably arranged in presentinvention contemplates the use of a. novel spiral. relation upon thescanning disk. type of-scanning disk which may be used with a In Fig. '1the rectangle A' represents a small source of'lightof high intensity andis provided, intensely brightly illuminated, area on the back with lightvalves adapted to be controlled by side of a scanning disk I H! which ismade of nonimpulsestfroma television receiverfor governconductingmaterial. The light thrown on A 30; ing the quantity of light passingfrom the source comes preferably from an intense source of'lightthroughthe successive aperture of the. scanning shown in Fig. 2 as anarc IH behind which is a disk. Through the medium of this. apparatus Ireflector H2 and in front of which is a condense I am able to reproducethetelevised image with a ing.- lens ll3. This source of. light and lensare much'brighter light which may be magnified. so. so arranged'as tothrow on a Nicol prism H4 a as to produce a sharp image of much. greaterbeam of light, which is limited to the desired proportions than hasheretoforebeen possible. square area by means of an opaque frame H5.

The construction of a preferredembodiment A succession of apertureslllil preferably round. of my invention, together with other objects atin form,is arranged in-the usual spiral form pierc- 40-tending itsproduction, will be best understood ing the non-conducting scanning diskIII], as 40 from the following descriptionof the accompanyclearly shown;in. Fig. 1. Behind each aperture ing drawings which are chosen forillustrative is.p1aced.a-smallKerr cell I H in such a manner purposesonlyand in whichthatthe portion of the light of the brightly il- 1- is.an elevational view showing animluminatedareaAwhich passesthrough agiven provedtype of scanning disk contemplated by aperture H6 must alsopass through the indivdual 5 thisinvention; p Kerr. celllocated directlyin frontof said aper- Fig. 21 is an end elevation illustrating themanture. nerof-utilizing the scanning disk shown in Fig. 1; One armatureof each Kerr cell is connected Fig. 3 is an elevational View similar toFig. 2, by means of the suitable conductor M9 to a corshowing a modifiedform ofscanning disk; responding segment I20. of a commutator Hi 50,Fig.4 isan elevational viewillustrating a modiwhich is arranged around ashaft I22 which carfiedform' of Kerr-cell construction which may be riesthe disk. Theseveral commutator segments employedin the-devicecontemplated by this inare so dimensioned. and spacedand, a brush I23vention; is so placed that only the active armature of the Fig; 5, is a.sectional view which may be con- Kerr cell which is at that momenttraversingthe 55,

532,454,, now Patent No. 2,026,872 dated January 7, 1936. Divided-andthis application September S, 1931, Serial No. 561,512

10 Claims.

sideredgashaving been. taken in a plane represented by the line .5-5 inFig. 4

Fig 6 isa sectional view illustrating the manner. of mounting thecellconstruction shown in illuminated area A is connected in theelectric circuit. The other armature of each of the Kerr cells isconnected to a common conductor I24. This common or bus conductor isconnected through a conductor I24 to the metal shaft I22 which carriesthe scanning disk I I0. The brush I23 and shaft I22 are connectedthrough conductors I25 and I26 to the output terminals of the secondaryI21 of a transformer I28. Inserted in series in this secondary circuitare high voltage polarizing batteries I29, the purpose of which is toimpress across the armature of Whichever Kerr cell happens to be incircuit a constant high voltage polarizing potential. The output of atelevision receiver amplifier (not shown) is led to the terminals of theprimary I30 of the transformer I28. By the above described arrangement,which is the usual circuit arrangement for modulating or valving lighttransmitted through a Kerr cell by means of received alternating currentenergy, as employed in talking picture recording and in certainpreviously known television receiving systems, I am able to modulate, or

valve, the light which is passing through a given 25 aperture on thescanning disk, because as is well known, the action of the Kerr cell isto elliptically polarize the beam of light, which, from practicalconsiderations, is the equivalent of rotating through a greater or lessangle the plane of polarization of a polarized light beam passedtherethrough.

As shown in Fig. 2, I provide in front of the scanning disk and directlyopposite the polarizing Nicol prism II4, the analyzing prism I I4a whoseaxis is turned through 90 relative to the angle of the first. In frontof this second prism at a suitable distance I place a projecting lens I3I by means of which the small image which passes through the prism IMat is enlarged and thrown upon a screen I32, so that the enlarged imageis seen, preferably by reversed projection, by the eye of the observerat I33.

The arrangement I have just described possesses many advantages over theheretofore used devices for television projecting wherein a single Kerrcell is employed to valve the concentrated light from a powerful arclamp, and said valved light beam thereafter being distributed over thescreen by means of a scanning disk containing lenses arranged inspiraled relationship. For example, by my method only a small portion ofthe light passes through any one Kerr cell, by virtue of which the cellis not subjected to damaging heat. Moreover, the cells are kept in veryrapid motion and thereby very effectively air-cooled. Furthermore, theNicol prisms are not subjected to the intense heat of a point ofconcentrated arc beam, as is the case where a single Kerr cell and smallNicol prisms are employed.

Fig. 2 shows the synchronized motor I driving by means of thespeed-multiplying gears I36I3'I the shaft carrying the scanning diskIII] and commutator I2I. The shaft and circuit are shown grounded at E,(Fig. 5).

I38 shows the 3 leads to the conventional three phase motor I35. I haveshown no detailed means for synchronizing the scanning disk at thereceiver with that at the distant transmitting station, inasmuch as Isynchronize my receiver by any one of the well known and effecivesynchronizing systems, and as this forms no part of my present inventionit is unnecessary to go into detail regarding same at this time.

Fig. 3 shows a somewhat improved method of using the Kerr cell andcommutator, whereby troubles of contact commutation between a fixedbrush and rapidly moving commutator segments are avoided. In thearrangement shown in this figure the individual Kerr cells III arearranged in spiral relationship as before, with the one armature of eachconnected to the common bus bar I24 which is connected, preferably bymeans of four conductors I40, 90 degrees apart, to the shaft I22 of the.scanning disk IIO, thence through the conductor to one terminal of thepolarizing battery I29 and preferably grounded. The other terminal ofthis polarizing battery is led through the secondary I2I of thetransformer I28, as described in connection with this same circuit asshown in Fig. l and thence through the conductor I25 to the insulatedplate I4I.

Around the circular periphery of the scanning disk I I0 is arranged aseries of conducting plates I42 of considerable area. The outer surfacesof these plates are turned to conform with the curvature of the scanningdisk, and fixed plate I4I, similarly curved, is so arranged as to comein very close proximity to, but not quite in contact with the sectorsI42. Each sector I42 is then connected by means of a wire I43 to theinsulated armature of its appropriate Kerr cell, (I I1) as is clearlyshown in Fig. 3. Inasmuch as the capacity of the condenser formedbetween fixed plate MI and any individual moving armature plate I42 onthe periphery of the scanning disk is thus made large compared with thecapacity of any individual Kerr cell the electrical action across theKerr cell which is thus put into circuit is essentially the same as thatshown in Fig. 1. If desired, a stopping, or safety condenser C can beinserted in the circuit of Fig. 1, as well as in that of Fig. 3, andotherwise the operation of the arrangement shown in Fig. 3 isidentically the same as that above described in connection with Fig. 1.

As a further modification of this arrangement of a multiplicity of Kerrcells in spiral formation upon a scanning disk, I have shown in Fig. 4 asingle glass tube I50 arranged in the proper spiral form and carrying onits inner shorter face a common conductor, or armature, I5I Oppositethis conductor and at an appropriate distance therefrom, and suitablyspaced relative to each other, are a series of small armatures I52, alead from each of which is brought out through the wall of the glasstube and led to its corresponding large-area plates I4I. These platesare arranged as shown in Fig. 3 about the circular periphery of thescanning disk.

The common conductor I5I may be in the form of a metallic conductordeposited on the inside of the spiral formed glass tube, or may belocated on the outside thereof, leaving only one set of armatures of theKerr cell inside the glass tube. This glass tube is preferably notcircular in cross section, but is flattened as shown in Fig. 5, whichfigure shows clearly the common armature I5I, in this case locatedoutside of the glass tube on its bottom surface, and an individual shortarmature of the Kerr cell I52 10- cated inside of the glass tube withits lead I53 brought out through the flattened wall of the tube, sealedtherethrough, and carried on to the conducting plate I42. The fixedcondenser armature plate I4I is also shown in close proximity to themoving plate I42 and connected to the conductor I 25a. I

Inasmuch as the action of the Kerr cell to equivalently rotate the planeof polarization of the light beam is more effective thebloser togetherare the two armatures, or electrodes, of the Kerr cell, I prefer tolocate the individual armature of :said' cell close to-th'e flattenedbottom of the glass tube; '1' prefer to leave a gap of say tenone-thousandths of an inch between the armature I52 and the bottom wallof the tube, or between the two metal armatures of the Kerr cell in caseboth armatures are placed within the glass vessel. The most suitablemetal for such Kerr cells armatures I have found to be gold, or someother suitable metal gold-plated. I prefer to use as my light rotatingliquid in the Kerr cell a solution of nitro-benzol.

Fig. 6 shows how the spiral formed glass vessel containing themultiplicity of Kerr cells is attached to one face of the insulatingscanning disk. The glass tube is supported on the metal bracket I60which is fastened by suitable means to one side of the scanning disklllla. This figure shows a small aperture IBI drilled through the faceof the scanning disk whereby a small beam of light is permitted to passthrough the Kerr cell after having traversed the polarizing Nicol prism2 I4. Having traversed the space between the armatures of the Kerr celland having its plane of polarization more or less rotated by suchpassage the beam of light is shown thence passing through the analyzingNicol prism 2l4a.

In Fig. 7, I have shown one form of small individual Kerr cellconsisting of an elongated glass capsule I65 containing two metalarmatures l l1a-l lBa, suitably separated, each with its lead broughtout through an opposite end of the capsule, as shown by H9 and l24a.Reference numeral I66 indicates the extension of the glass envelope,whereby the Kerr cell is filled with nitro-benzol solution and thensealed off. These individual Kerr cells are then mounted in properrelationship around the scanning disk and the armature is connectedrespectively to the common conductor and to the individual commutatorleads as described in connection with Fig. 1 or Fi 3.

Fig. 8 shows a sectional view of one of these individual Kerr cellstaken at right angles to the view shown in Fig. 7. It is here seen thatthe passage of the beam of light, indicated by arrow B, is through thesmall diameter of the glass envelope, and between the two armatureplates of the cell. I so place these individual Kerr cells that theprolongation I66 is pointed towards the center of the scanning disk sothat when the disk is in rapid rotation centrifugal force causes thefluid to completely fill the space between and surrounding the twoarmatures of the cell, leaving the air bubble (which is usually presentafter sealing off the glass capsule) in'the prolongation of the capsule.

Many other modifications and changes in details will occur to thoseskilled in the art without 1. For use in a television receiver: ascanning disk provided with a multiplicity of apertures; a Kerr cell ateach of said apertures; means for rotatlrigsaid iscanning "disk; and.means for electrl callychargingthe successive Kerr cells from'a.television receiver during. the rotation. of said disk. I

2. use atelevision receiver: a scanning diskpi ovid'ed witha;rnu-l'tiplicity of apertures; a Kerr cell at each of said apertures; acommutator on -sajid s'canning disk; means for connecting one armatureof each Kerr cell to one segment of said commutator; a common conductoron said scanning disk; means for connecting the other armature of eachKerr cell to said common conductor; and means for connecting the commonconductor and the successive segments of said commutator to the outputof a television receiver.

3. For use in a television receiver: a scanning disk provided with amultiplicity of apertures; a Kerr cell at each of said apertures; aseries of commutator segments on the periphery of said disk; meansconnecting one armature of each Kerr cell to one of said commutatorsegments; a common conductor on said disk; means for connecting theother armature of each Kerr cell to said common conductor; and means forconnecting the successive commutator segments and the said commonconductor to the output of a television receiver.

4. For use in a television receiver: a scanning device embodying; ascanning disk provided with a multiplicity of apertures arranged in aspiral path; a transparent tube containing a polarizing fluid mounted onsaid disk opposite the apertures therein; means for rotating saidscanning disk; means for projecting a beam of polarized light towardsaid disk and over an area traversed by said apertures; a plurality ofarmatures on opposite sides of said tube adjacent said apertures; meansfor connecting said armatures with the output of a television receiverduring the movement of said aperture through the illuminated area; andan analyzing prism for passing the light coming from said apertures.

5. For use in a television receiver: a scanning device embodying; ascanning disk provided with a multiplicity of apertures arranged in aspiral path; a Kerr cell mounted on said disk at each aperture; meansfor rotating said scanning disk; means for illuminating an area of saiddisk traversed by said apertures with a beam of polarized light; meansfor energizing each Kerr cell during its movement through theilluminated area from a television receiver; and an analyzing prism forpassing the light coming from the successive Kerr cells.

6. For use in a television receiver: a scanning disk provided with a.multiplicity of spirally arranged apertures; means for rotating saiddisk; a spiral tube filled with polarizing fluid mounted on said diskopposite said apertures; armatures on opposite sides of said tubeadjacent said apertures; and-means for connecting said armatures withthe output of a television receiver during the movement of saidapertures through a predetermined area.

7. In combination a rotatable scanning member provided with a pluralityof scanning apertures, a Kerr cell for each aperture, a commutator,means connecting one armature of each Kerr cell to a correspondingsegment of said commutator, a common conductor, means connecting theother armature of each Kerr cell to said common conductor, and meansconnecting the currentconductor and the segments of said commutatorsuccessively to the output of a television receiver.

8. In combination a rotatable perforated scanner having a plurality ofscanning apertures and a plurality of sets of Kerr cell electrodescarried by said member, there being one 5 set of electrodes adjacenteach of said apertures, and a polarizing medium between each set ofelectrodes.

9. The combination according to claim 8, in

which all the said sets of electrodes are mounted within a singleenclosing envelope.

10. The combination according to claim 8, in which the said sets ofelectrodes are mounted within a common spiral enclosing envelopecontaining a solution of nitro-benzol.

LEE DE FOREST.

